Automated fiber placement machines are widely used to manufacture parts, components and structures from composite material. The materials used in automated fiber placement are typically composed of longitudinal fibers and resin consolidated into tapes or thin strips commonly known as “tows.” The individual tapes or tows are manipulated by the fiber placement machine to form a band of material that is deposited onto a mold or tool. Parts are built up layer-by-layer, with tapes or tows of composite material, with the angle at which each layer or “ply” is laid onto the tool being precisely determined by the fiber placement machine.
Automated fiber placement enables the construction of complex composite structures having steered or curvilinear fiber paths. This method of producing composite structures is more cost effective than manual methods. It provides an improved structural efficiency due to its ability to orient the fibers along local internal loads paths, which potentially results in lighter structures and lower cost than in structures made by other production methods.
The tool that the composite material is laid onto is often quite complex, in that the geometry of the finished part is machined into the tool surface. Depending upon the desired result, the tool may have the form of the outside “Outer Mold Line—OML” or the inside “Inside Mold Line—IML”.
The individual tows of material are typically wound onto spools, stored in an environmentally-controlled structure known as a creel. A single creel may commonly include for example, provisions for storage and simultaneous out-feed from 32 spools. During the fiber placement process, particularly on large parts, the tows stored on one or more of the spools may be completely used up, prior to the completion of the part.
In order to reduce the time and cost required for forming large or complex structures, such as those manufactured in the aerospace or aircraft industries, it is desirable to utilize multiple automated fiber placement machines. In order to efficiently and safely utilize multiple automated fiber placement machines for the effective laying of fibers onto a common tool surface, it is necessary that an apparatus and method for simultaneously controlling multiple fiber placement machines be provided. Consistent with this desire is the ability to manufacture particularly large pieces with a minimum of lost or “down time” spent on replenishing composite fiber creels for application. It would be desirable to have an apparatus and method that would allow for composite fiber application and simultaneous creel replenishment.
In order to accomplish the fabrication of either large or complex parts, it is also desirable that a method and apparatus be provided for replenishing the supplies of composite materials available to the automatic fiber placement machines without interrupting the fiber placement process by shutting down all of the machines, when any one of the fiber placement heads needs to have its supply of composite materials replenished. In similar fashion it is desirable to have the capability of changing-out the fiber placement heads of the fiber placement machines, without interruption of the fiber placement process so that the heads may be periodically serviced and cleaned to maintain optimal operating speeds of the fiber placement process.
It is desirable, therefore, to provide a method and/or apparatus for replenishing the exhausted spool as quickly and efficiently as possible, so as to minimize interruption of the fiber placement process. As identified in U.S. Provisional Patent Application No. 60/564,154, filed Apr. 21, 2004, now U.S. Non-Provisional application Ser. No. 11/111,499, filed Apr. 21, 2005, it is also highly desirable to provide a method and/or apparatus for replacing either an entire creel assembly and inventory in order to provide an efficient, uniform supply of the required creels in the correct tow widths, while having the exhausted creel assembly either replenished with more of the same required supply, or; replaced with alternative or different dimensioned tow supplies for alternative or different applications.
Further, as identified in U. S. Provisional Patent Application No. 60/711,290, filed Aug. 25, 2005, now U.S. Non-Provisional application Ser. No. 11/510,165, filed Aug. 25, 2006, it is also desirable that both the fiber placement head and support structure for the fiber placement head be a compact, rugged, simple construction that allows maximum access for threading the multiple tows of fiber through the support structure and placement head onto either a large, or small complex or curvilinear mold line being presented on either a rotating mandrel or stationary tablet.
It is also highly desirable to have a system of fiber placement machines that can accommodate a complex design of composite fiber placement involving multiple applications of multiple width tows and multiple width compaction rollers in an efficient mode of interchangeability.